Process for the manufacture of finely porous butadiene-styrene copolymers



United States atent PROCESS FOR THE MANUFACTURE OF FINELY POROUS BUTADIENE-STYRENE COPOLYMERS 2,891,016 Patented June 16, 1959 5 As substances to be rendered porous by the process Rudolf Kern, Neustadt, and Wilhelm N. Grohs, Heidelof the invention there may be mentioned natural or synberg, Germany, assignors to Rhein-Chemie G.m.b.H., thetic rubber and rubber-like artificial resins, for example, Mannheim-M16113", Germany polymerization products such as copolymers: of butadiene and styrene. No g fi g ag st 1956 The following examples illustrate the invention. In

these examples, which describe rubber or artificial resin Claims P y, application Germany August a 1955 mixes, two comparative tests A and B are carried out, tests A being carried out with a blowing agent alone, and 4 Claims 260 r tests B with a blowing agent and also a substance reduci a This invention relates to processes of the kind in which g ga g gg 5 2 3: g 332 2;? gl g g g gfi finely porous orgamc matenals of i i i struc' uniformly distributed than in the case of the vulcanisates Such as those of ruijber or artlficlal are obtained in tests A. This applies also to those examples duced by mealis of blowuig agents 1 blqwmg agents in which this result is not specifically mentioned. Furtherhave the funcnon of blowmg l l lmpartmg a porous 29 more in tests B the volume of the body removed from Structure to material by sphttmg ofi The gas the mould was greater than that in the case of tests A. is Splii i dunpg l treatment to Wh1.ch the rubber The increases in volume coupled with the lowering of or amficlal resm 1S Sublected' The blowmg up of i the specific gravities of vulcanisates B were measured as mass causes small gas bubbles to become embedded in compared with those of Vulcanisates A and are given its structure, and results in decreasing the specific gravity 5 below in each test and heat conductivity of the material. The porous Example 1 structure of the material is fixed by vulcanisation or a gelatinising Process A rubber mix was prepared having the composition:

This method of rendering rubber or artificial resins pale crepe rubber 50 porous is u d, o e esp y. for making products so copolymer of butadiene and styrene 50 of low specific gravity and low heat conductivity such, for Thiofimaphthol ()4 example, as the soles of shoes, mats, cushions, etc. How- Calcium silicate 60 ever, the process is also applicable when porosity as such Kaolin 30 is required or for the purpose of absorption in chemical pararhn wax 1 industry- Stearic acid 4 In the process of the present invention there are used White petroleum jelly 5 gas-evolving blowing agents, other than nitrosamines, for Zinc oxide example, sodium bicarbonate, ammonium bicarbonate, h/h-Xture of dibenzthiazyl disulphide and diphehylammonium carbonate, benzene sulphonic acid hydrazide, guanrdihe 1.5 diazo-aminobenzene, urea, azo-butyric acid nitrile or mix- 40 Sulphur 5 tures of ammonium compounds with alkali nitrites. These substances are incorporated in the rubber or artificial res- 208.4 ins in a proportion such that during the usual heat treat- The crepe rubber, coplymer of hurarhehe and styrene and ment a more or less strongly porous structure is produced. the throhqraphthcl wrre first premasticated f 10 The present invention is based on the observation that minutes on rollers heated at C and then the fining the action of thfise -9 P K agfimts can be material, plasticiser, zinc oxide and finally the accelerator improved by using them in con unction with surfaceand sulphur were incorporated in the mixture at active substances which reduce the surface tension. The surface'active substance may be mixed with the material The final mixture was divided into two harm which is to be rendered porous, so that the former is 50 (A) 100 grams of the above mixture were mixed with brought into contact with the blowing agent only when 8 gramswof sodium bicarbonate. the latter is mixed with the material to be rendered (B) 100 grams of the same rubber mix were mixed porous. Alternatively, the surface-active substance may with 13 grams of a mixture f 8 grams 0f sodium first be mixed with the blowing agent, advantageously by carbonate and 5 grams of a paste f 60 percent strength means of apparatus such as a roller mill, colour mill, of sodium dodecyhhenzerre sulphonatel colloid mill or the like, so that a homogeneous mixture is The latter mixture was prepared as f ll obtained. In some cases it is of advantage to form the 200 grams of Sodium carbonate were dissolved in blowing agent in the presence of the surface-active sub- 1000 grams f water, and 10 grams f sodium d 1 Stance, Q that the blowing agent is obtained In a Very benzene sulphonate were added. A strong current of finely dlvlded i carbon dioxide was passed through the mixture for about By the addition of the surface-active substance the ac- 5 hours whereby sodium bicarbonate was precipitated tion of the blowing agent is unexpectedly improved in sevin a very finely divided form The Sodium bicarhchats eral ways. The gas pores in the finished product are more was filt d 5 with suction, cautiously dried, and then uniformly distributed and are finer, and the product has weighed about 5 granm 3 grams f the resulting i a lower Specific gravity and IOWEI heat Conductivityture were intimately triturated on a roller mill with 5 Any surface-active substance capable of reducing the grams f a paste f 69 percent strength f di d d Surface tension y be used in the Process of the inveflbenzene sulphonate. The mixture was then added to the tion, such as alkyl-aryl sulphonates, for example, sodium r bb i dodecyl-benzene sulphonate; sulphated fatty alcohols, for 70 Test portions of the above compositions (A) and (B) example, the sodium salt of a sulphated mixture of fatty alcohols containing 10-16 carbon atoms; or quaternary ammonium salts containing a radical of high molecular were heated under exactly the same conditions in a vuloanising press in closed moulds for 20 minutes at 141 C. l

The vulcanisate produced with composition (B) had a considerably larger volume and also finer and more uni form pores than those of the vulcanisate made from composition (A). Vulcanisate;(A) had a specific gravity of 1.140 and vulcanisate (B). a specific gravity of 0.864.

Example 2 (A) To 100 grams of the rubber mix described in Example 1 were added 3 grams of ammonium bicarbonate.

(B) To 100 grams of the same rubber mix was added a mixture of 3 gramsof ammonium bicarbonate and 3.3 grams of a paste of 77 percent strength of oleylj-benzyldimethyl-ammonium chloride.

Test portions of each composition were heated under exactly the same conditions in a vulcanising press in closed moulds for 20 minutes at 141 C. The specific gravity of vulcanisate (A) was 0.638 and that of vulcanisate (B) was 0.456.

Example 3 (A) 100 grams of therubber mix describedin Example 1 were mixed with 3.0 grams of benzene sulphonic acid hydrazide.

(B) 100 grams of the same rubber mix were mixed with 5.0 grams of a mixture prepared as follows:

3 grams of benzene sulphonic acid hydrazide 'were intimately triturated in a roller mill with 2v grams of a paste of 50 percent strength of the sodium salt oi the sulphate of a mixture, of fatty alcohols containing 10-16 carbon atoms. e

Compositions (A) and (B) were each heated under exactly the same conditions in a vulcanising press in closed moulds'fo'r 20 minutes at 141 C. The specific gravity of vulcanisate (A) was 0.505 and that of vulcanisate (B) was 0.452.

Example 4 A rubber mix'was prepared having the composition: Pale crepe rubber lq 70 p ymer f. hutad ne and Yr 30 Zinc compound of pentachlorothiophenol 0.3 Zinc salt of rape seed oil fatty acid 3.0

The mixture was premasticated for 10 minutes at 110 C; on rollers, and then there were added at'0-'6'0 C.

Calcium silicate 50 The above mixture was divided into two parts:

(A) To 100 parts of the rubber mix 8. grams of sodium bicarbonate were added.

(B) To 100 grams of the rubber mix were added 13 grams of a preparation obtained by mixing 80 parts by weight of sodium bicarbonate with 50 parts by weight of a commercial preparation of sodium dodecyl-benzene sulphonate of 6'0 percent strength. Thus, mixture (B) also contained 8 grams or sodium bicarbonate.

Test bodies made from mixtures (A) and (B) were heated under exactly the same conditions for 15 minutes at 143 C. in a vulcanisation press in a closed mould. The specimens became inflated and vulcanised. The vulcanised test body (A) had a specific gravity of 0.990, and the vulcanised body B had a specific gravity of 0.707.

Example 5 The rubber mix described in Example 4 was divided into two portions: 7 k

(A) To grams of the rubber mix 8 grams of sodium bicarbonate were added.

(B) To 100 grams of the rubber were added 13 grams of the preparation prepared with sodium bicarbonate and sodium dodecyl-benzene sulphonate as described in Example 1, the aforesaid quantity'ofthe preparation containing 8 grams of sodium bicarbonate.

Test bodies made with mixtures (A) and (B) were heated under exactly the same conditions in a vulcanisation pressin ,a closed mould for 15 minutes at 133. C. In this manner the test bodies became inflated and vulcanifsed. The vulcanisate (A) had a specific gravity of 0.478 and the vulcanisate (B) a specific gravity of 0.603.

We claim:

1. A process for the manufacture of materials having a finely cellular substantially fine pore structure; which comprises first intimately mixing together a surface-active agent and as a blowing agent a compound, selected from the group consisting of ammonium bicarbonate, am monium carbonate, benzene sulphonic acid hydraiide and urea whichevolves on thermal decomposition a gas selected from the group consisting of carbon dioxide, ammonia arid sulphur dioxide, thereafter intimately incorporati'ng the resulting mixture in an uncured copoly mer of bntadiene and styrene, and subsequently curing the mixture with the aid of heat to produce a material having a substantially closed pore structure.

2. A process for the manufacture of materials having a finely cellular substantially fine pore structure; which comprises intimately mixing together a surface-active agent and as a blowing agent a compound, selected from the group consisting of sodium bicarbonate, ammonium bicarbonate, ammonium carbonate and beniene' sulphonic acid hydrazide, which evolves on thermal decomposition a gas selected from the group consisting of carbon dioxide, ammonia and sulphur dioxide, thereafter intimately incorporating the resulting mixture in an uncured copolymer of butadiene and styrene and subsequently curing the mixture with the aid of heat to producea material having a substantially closed pore structure.

3. A process as claimed in claim 2 wherein the blowwith a fatty alcohol.

References Cited in the file of this patent 1 UNITED STATES PATENTS 

1. A PROCESS FOR THE MANUFACTURE OF MATERIALS HAVING A FINELY CELLULAR SUBSTANTIALLY FINE PORE STURCTURE; WHICH COMPRISES FIRST INTIMATELY MIXING TOGHETER A SURFACE-ACTIVE AGENT AND AS A BLOWING AGENT A COMPOUND, SELECTED FROM THE GROUP CONSISTING OF AMMONIUM BICARBONATE, AMMONIUM CARBONATE, BENZENE SULPHONIC ACID HYDRAZIDE AND UREA WHICH EVOLVES ON THERMAL DECOMPOSITON A GAS SELECTED FROM THE GROUP CONSISTING OF CARBON DIOXIDE, AMMONIA AND SULPHUR DIOXIDE, THEREAFTER INTIMATELY INCORPORTATING THE RESULTING MIXTURE IN AN UNCURED POLOLYMER OF BUTADIENE AND STYRENE, AND SUBSEQUENTLY CURING THE MIXTURE WITH THE ACID OF HEAT TO PRODUCE A MATERIAL HAVING A SUBSTANTIALLY CLOSED PORE STRUCTURE. 